From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752739Ab1C2G1O (ORCPT ); Tue, 29 Mar 2011 02:27:14 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:49513 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456Ab1C2G1N (ORCPT ); Tue, 29 Mar 2011 02:27:13 -0400 Date: Tue, 29 Mar 2011 08:27:06 +0200 From: Ingo Molnar To: Andy Lutomirski Cc: x86@kernel.org, linux-kernel@vger.kernel.org, John Stultz , Thomas Gleixner Subject: Re: [PATCH 0/6] x86-64: Micro-optimize vclock_gettime Message-ID: <20110329062706.GE27398@elte.hu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andy Lutomirski wrote: > This series speeds up vclock_gettime(CLOCK_MONOTONIC) on by almost 30% > (tested on Sandy Bridge). They're ordered in roughly decreasing order > of improvement. > > These are meant for 2.6.40, but if anyone wants to take some of them > for 2.6.39 I won't object. > > The changes and timings (fastest of 20 trials of 100M iters on Sandy > Bridge) are: > > Unpatched: > > CLOCK_MONOTONIC: 22.09ns > CLOCK_REALTIME_COARSE: 4.23ns > CLOCK_MONOTONIC_COARSE: 5.65ns [ Patched: ] > CLOCK_MONOTONIC: 15.66ns > CLOCK_REALTIME_COARSE: 3.44ns > CLOCK_MONOTONIC_COARSE: 4.23ns That looks like a nice speedup, and speedups are definitely welcome. Many of your speedup patches were framed in an unclean or hard to maintain fashion though - so those have to be improved for this series to become palatable. Thanks, Ingo